The present invention relates to a pharmaceutical composition for treating osteoporosis, which contains a compound of 24,25-dihydroxycholecalciferol as an active ingredient.
In recent years, the average life span of the Japanese has rapidly extended, and accordingly the population of people of age of more than 65 is now more than ten millions. Consequently, the population of the patients treated as those suffering from osteoporosis is presumed to be as many as 3 millions.
Accordingly, the elucidation of the morbid state and the establishment of the therapy of osteoporosis are very important problems, and the development of the safe medicine for treating osteoporosis has been keenly expected.
Although it is considered that the occurrence of osteoporosis is due to several causes such as endocrinical causes, nutritive causes, physical causes, hereditary causes, etc., cases of postmenopausal osteoporosis occupies the largest percentage of all the cases of osteoporosis.
An activated vitamin D.sub.3, for instance, 1.alpha.-hydoroxycholecalciferol or 1.alpha.,25-dihydroxycholecalciferol, is used as an active ingredient of the pharmaceutical composition for treating osteoporosis and the activated vitamin D.sub.3 is chemically similar to the present substance, however, there is a side-effect problem in the administration of such an activated vitamin D.sub.3 and accordingly, it is necessary to pay a close attention in administering such an activated vitamin D.sub.3.
In addition, although the effect of the activated vitamin D.sub.3 on the bones of the patient administered therewith is determined by the extent of promotion of absorption of calcium via the intestinal tracts of the patient, such a determination is an indirect determination and it has not been elucidated that there is any direct interrelationship between the extent of promotion of absorption of calcium and the lesion of the bone due to osteoporosis.
In consideration of the above-mentioned situation, the present inventors have studied for the substance utilizable for treating osteoporosis, particularly among the safe and endogenous substances present in healthy human body while examining the antiosteoporotic activity, thereof and as a result, the present inventors have found out that the compounds of 24,25-dihydroxycholecalciferol (hereinafter abbreviated and referred to as 24,25-(OH).sub.2 -D.sub.3, or more simply as the present substance) have an activity of directly improving the lesion of bones due to osteoporosis to a remarkable extent without exhibiting any side-effects and toxicity, and have attained the present invention.
Osteoporosis referred to in the present invention includes not only senile osteoporosis and postmenopausal osteoporosis but also secondary osteomalacial osteoporosis accompanying osteomalacia, secondary osteoporosis accompanying functional accentuation of the accessory thyroid and topical osteoporosis and abnormal bone both due to articular rheumatism.